Brain Tumors down arrow

Home > Disclaimer > Astrocytoma

 

Astrocytoma

 

 

Classification

Astrocytomas are typically described as low grade astrocytomas (LGAs) or high grade astrocytomas (HGAs) based on pathological characteristics.

Low Grade Astrocytomas (LGA)

Localized

Grow slowly over a long period of time

Most LGA are of two types:

1. Pilocytic astrocytoma (PA)

    • World Health Organization [WHO] grade I
    • Circumscribed
    • Homogeneously neoplastic
    • Low potential for tissue infiltration or malignant degeneration
    • Lacks p53 changes, but may show loss of chromosome 17q in the region of
      the NF1 gene

2. Diffuse fibrillary astrocytoma (DA)

    • WHO grade II
    • Invasive tumor
    • Tendency to undergo malignant change (esp in adults)
    • Genetically distinct - associated frequently with p53 mutations or occasionally
      with loss of heterozygosity on chromosome 10p.

Other Low-Grade Astrocytomas:

  • Pleomorphic Xanthoastrocytoma (PXA)
    • Form of astrocytoma unique to children
    • More common in late childhood and early adolescence
  • Subependymal Giant Cell Astrocytoma
  • Dysembryoplastic Neuroepithelial Tumor (DNET)
    • some would argue that these are neuroepithelial tumors rather than gliomas
  • Ganglioglioma
  • Oligodendroglioma
  • Desmoplastic infantile ganglioglioma

Characteristics of Low-Grade Astrocytomas:

Juvenile

Pilocytic Astrocytoma(JPA)

Desmoplastic Cerebral Astrocytoma

Subependymal Giant Cell Astrocytoma

Fibrillary [P1]

Most Common

Patient Age

Early childhood

Usually <2 years

(infantile)

Early childhood, may be as early as neonatal period

30-40yrs

Most Common Tumor Location

Cerebellum

Cerebral hemispheres

Subependymal origin

 

Occur along lining of lateral ventricles

Brain parenchyma

 

May be supratentorial

Growth

Limited

Indolent nature

Invade leptomeninges

Grows to invade 4th ventricle

 

May obstruct foramen of Munro

Diffuse infiltration of parenchyma

 

Anaplastic progression

Histology

Well-circumscribed

 

Solid and cystic architectural pattern

 

Rosenthal fibers

 

Commonly has vascular proliferation

Highly spindled cells

 

Collagen

GFAP-reactive

Both glial and neuronal nature suggested

 

Reactive with both types of tumor markers

 

Lineage still debated

 

Large cells with abundant cytoplasm

 

Occasional calcification

 

Fibrillary pattern may be seen

Nuclei of normal astrocytes, but may be pleomorphic

 

No mitotic figures

 

No vascular proliferation

 

No necrosis

Special Features

Unique to children

Their association with basal lamina may be responsible for their indolent nature

 

Extracellular matrix proteins inhibit cell growth

Associated with tuberous sclerosis[P2]

Lack contrast enhancement

Prognosis

Very good:

  • Indolent nature
  • -Long term prognosis related to location

Favorable, even with large size

Total resection is the best option for progression-free survival

 

High-grade astrocytomas

  • Worse prognosis than LGA
    • Higher rate of neuraxis dissemination
    • Grow rapidly
  • Two main classes of high grade astrocytomas:
    • anaplastic astrocytomas
    • glioblastoma multiforme

Characteristics of High Grade Astrocytomas:

Anaplastic Astrocytoma

Glioblastoma Multiforme (GBM)

Patient Age

Uncommon in children

 

Tend to occur in adults

(median age 40yrs)

Uncommon in children

 

Tend to occur in adults (median age 45-70yrs).

Tumor Location

Cerebral hemispheres

Brain stem

Subcortical white matter of cerebral hemispheres

Histology

Increase in cellularity

 

Nuclear pleomorphism

 

Hyperchromasia

 

May have mitosis & vascular proliferation

 

No necrosis

  • if present, would be GBM

Dense cellularity

 

Mitotic figures

 

Vascular proliferation

 

Necrosis is present

Prognosis

High incidence of progression to glioblastoma

Very poor prognosis

 

External Link:

Overview of Astrocytomas at the Atlas of Genetics and Cytogenetics in Haematology and Oncology

 

 

Back to top

Next